Dosage & administration :
Administration
Risperidone is administered orally without regard to meals.
* For the treatment of schizophrenia :
Adults and adolescents: On the first day, 2 mg by oral as a single dose or in
two divided doses. Titrate upwards on the second day to 4 mg by oral as a single
dose or in two divided doses. On the 3rd day, titrate upwards to 6 mg by oral as
a single dose or in two divided doses. Slower titration may be needed in some
patients. If further dosage adjustments are indicated, increments or decrements
of 2 mg per day at weekly intervals are recommended. In general the
effectiveness of doses above 6 mg day have not been demonstrated, and may
increase the risk of extrapyramidal symptoms.
Elderly and patients with impaired hepatic function: Initially 0.5 mg by oral
twice a day. Increase dosage by 0.5 mg twice a day, with increases above the
level of 1.5 mg twice daily only occuring at intervals of one week.
Children under age 15 years: Safe use in children under age 15 years has not
been established.
* Patients with renal impairment :
Dosage should be modified depending on clinical response and degree of renal
impairment. Initially 0.5 mg by oral twice a day. Increase dosage by 0.5 mg
twice a day, with increases above the level of 1.5 mg twice a day only occuring
at intervals of one week.
Contraindications :
Risperidone is contraindicated in :
* Breast-feeding. * Children under age 15 years
Precaution
:
Risperidone should be used cautiously in patients with:
- Preexisting hypotension or cerebrovascular disease.
- Cardiac disease, especially those with heart failure, history of myocardial
infarction or ischemia, or conduction abnormalities.
- Existent QT prolongation can produce an increased risk of developing
arrhythmias. - Conditions that may predispose
patients to hypotension, such as hypovolemia and dehydration.
As with all schizophrenic patients, possible enhancement of suicidal ideation is
a reality in those taking risperidone. Close supervision and control of
medication is advisable.
- Parkinson's disease because of possible development of extrapyramidal symptoms.
seizure disorders or brain tumors.
Antiemesis produced by risperidone can obscure evidence of GI obstruction or
ileus.
- Breast cancer.
Drug interaction:
* B-blockers increase risperidone plasma concentrations.
*
Carbamazepine or phenobarbital increase the metabolism of risperidone and
potentially decrease its effectiveness.
* Cimetidine may increase the risk of developing risperidone-induced
extrapyramidal symptoms.
* Risperidone leads to a marked elevation of clozapine serum concentrations.
* Fluoxetine induces tardive dyskinesia.
* Haloperidol the risk of additive toxicity.
* Levodopa & bromocriptine opposites of risperidone.
* Phenothiazines the risk of additive toxicity.
* Tricyclic antidepressants increases in plasma levels of either drug.
Side effects:
- Abdominal pain - agitation - anxiety
-blurred vision - constipation - dizziness
- drowsiness - dyspepsia - dystonic reaction
- ejaculation dysfunction - fatigue
-
headache
- impotence - insomnia - libido decrease
- libido increase - menstrual irregularity -
nausea/vomiting
- neuroleptic malignant syndrome - orthostatic hypotension
- parkinsonism - photosensitivity
-
QT prolongation
- rhinitis - salivation - syncope
- ventricular tachycardia - weight gain - withdrawal
Overdosage :
Symptoms :
- Drowsiness and sedation. - Tachycardia & hypotension.
- Extra pyramidal symptoms . - Rarely QT prolongation.
Treatment :
- Adequate oxygenation and ventilation.
- Gastric lavage (if the patient is unconscious)
- Administration of activated charcoal together with laxative.
- There is no specific antidote for Risperidone therefore appropriate supportive
measures should instituted :
* hypotension and circulatory collapse should be treated with intravenous fluid
and/or sympathomimetic agent.
* In case of sever extra pyramidal symptoms anticholinergic medication should be
administered.
* Cardiovascular monitoring should commence immediately and should include
continuous ECG monitoring to detect possible arrhythmia.
Instructions to the patients:
-
Risperidone can help you to keep in touch with reality and reduce your mental
problems.
- Swallow the tablets with a drink of water. If risperidone upsets your stomach
you can take it with food. Take your doses at regular intervals. Do not take
your medicine more often than directed. Do not stop taking except on your
doctor's advice.
- Elderly patients over age 65 years may have a stronger reaction to this
medicine and need smaller doses.
- Tell your doctor or pharmacist: about all other medicines you are taking,
including non-prescription medicines; if you are a frequent user of drinks with
caffeine or alcohol; if you smoke; or if you use illegal drugs. These may affect
the way your medicine works. Check before stopping or starting any of your
medicines.
- Do not suddenly stop taking risperidone. You may need to gradually reduce the
dose. Only stop taking risperidone on your doctor's advice.
- You may get dizzy or drowsy. Do not drive, use machinery, or do anything that
needs mental alertness until you know how risperidone affects you.Avoid
alcoholic drinks. You can get a hangover effect the morning after a bedtime
dose.
- Risperidone may make you more sensitive to sun or ultraviolet light. Keep out
of the sun, or wear protective clothing outdoors and use a sunscreen (at least
SPF 15). Do not use sun lamps, . To protect your eyes wear sunglasses even on
cloudy days.
Pregnency & lactation :
* Risperidone is classified as pregnancy category C.
* The drug is recommended for use during pregnancy only when the benefits
outweigh the risks.
* The drug should not be used in breast-feeding women.
